Self-regulating two-channel time division telegraph system



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SELF-REGULATING Two-CHANNEL TIME; DIVISION TELEGRAPH SYSTEM Filed Sept. 1, 1959 18 Sheets-Sheet 18 .229m 52.5545 Mmm Iw. IFT- m ww @E ....5 gIV+ I I I I I I I I I I I I I I I mamQ Em mam wzmd zh wq 2m mnwzszEsJ A H m23@ 29m E Llama@ @www I I I I I||lI||| IIII @Fw .w H W m0 w W III om@ I I I III n H Hw Gzs: n H .H Il.. 8263.2 w. I I 5.5". 55 o I U w mmmoww p I mm mm I m2@ u nl. m2@ n mop $222. I m 559.355 w w EL mm2@ o I 1.1 m lll) HL |v+ r I||||I I I I I I I I I I I I |I| ..II...O P l I l |||I|l Ll Il IIFIII n l n I- a l United States Patent O 3,114,603 SELF-REGULATING TWO-CHANNEL TIME DIVISIDN TELEGRAIH SYSTEM Harold F. Wilder, Wyckoii, NJ., assigner to The Western Union Telegraph Company, New York, N.Y., a corporation of New York Filed Sept. 1, 1959, Ser. No. 337,499 6 Claims. (Cl. 178-50) This invention concerns an unattended, self-regulating time division multiplex telegraph system capable of transmitting over a single narrow-band carrier channel two independent message channels.

At the transmitting or sending terminal of this system the intelligence pulses of the message characters are transmitted in discrete bursts of about one minute duration. Each burst of transmission is preceded by a rest period during which a number of impulses are transmitted to the `receiving station. The receiving station aligns its signal regenerative circuitry upon this alignment signal before restoring each of its multiplex channels to a condition `for receiving message traic signals from the transmitting terminal.

It has been known heretofore in diplex telegraph systems to precede each pair of characters sent with a common start pulse and add a rest pulse at their conclusion. In the present system by contrast several hundreds of characters are transmitted in each burst of transmission, with the bursts preceded by alignment or synchronizing signals.

The system further provides unique means for utilizing the alignment signals by providing ranging circuitry which insures that the scanning of the alignment signals is ef fected when their time function is maximum and the signal impulses are least susceptible to distortion and electrical noise eiects.

It is a principal object of the invention to provide a system in which all transmitting, receiving, and aligning operations are done automatically so that neither initially nor during course of use is the attention of testing and regulating personnel required.

It is a further object to provide a telegraph system in which operations of circuit lineup, channel phasing, and ranging are done automatically rather than manually.

It is another object to provide an runattended selfregulating, time division telegraph multiplex system.

A further object is to provide a telegraph system in which trafiic transmission is separated `into periodic bursts of predetermined numbers of characters, the length of time oi transmission being suthciently short to make it possible to use free running oscillators as standard vfrequency sources at sending and receiving terminals and to avoid the necessity of phase correction means at the receiving terminal.

A further object is employment in a telegraph system of an automatic signal ran-ging circuit which scans incoming signals at a receiving terminal at their center of time duration when they are least susceptible to signal bias and distortion.

A further object is provision of a ranging circuit which operates as an electronic clutch.

Other and further objects and advantages of the invention will become apparent from the following description taken together with the drawings, wherein:

FIGS. l and 2 taken together constitute a diagram of a signal sending terminal employed in the system;

FIG. 3 is a diagram showing graphically pulses employed in the system;

FIG. 4 is a block diagram of a receiving terminal employed in the system;

FIG. 5 is a perspective view of the multiple phase generator as employed in the system;

3,114,003 Patented Dec. 10, 1963 ICC FIG. 6 is a front elevational view partially schematic in form of the multiple phase generator;

FIG. 7 is a graphic diagram of the quadrature exciting currents in the multiple phase generator;

FIG. 8 is a schematic diagram of windings of the multiple phase generator;

FIG. 9 is a graphic diagram of voltages produced by the multiple phase generator;

FIG. l0 is a schematic diagram of gate circuits associated with the multiple phase generator;

FIG. 10A is a legend showing conductive states of transistors employed in the system;

FIG. l1 is a pulse diagram employed in explaining operation of the gate circuits;

FIG. 12 is a diagram of a typical chain of trigger circuits as employed in the system;

FIGS. 13 and 14 taken together constitute a ranging circuit employed in the system;

FIGS. 15-17, 15A-17A and 15E-17B are pulse diagrams employed in explaining the mode of operation of the ranging circuit;

FIG. 18 is a schematic diagram and FIG. 19 is a pulse diagram employing the electronic clutching action of the ranging circuit;

FIGS. 20 and 21 are diagrams of timer and counter circuits employed in the receiving terminal of the system;

FIG. 22 is a diagram of a four hundred operations counter employed at the receiving terminal;

FIGS. 23, 24 and 25 taken together constitute a diagram of a receiving multiplex distributor circuit; and

FIG. 26 is a diagram of a multiplex signal to teleprinter signal conversion circuit.

The system to be described employs transmission of tive-unit code message trafc common to landline telegraphy, but it can be readily adapted for handling six-unit code traffic such -as used in ocean cable telegraphy.

Signals lare transmitted on two channels, herein designated channel A and channel B. The system can be expanded, however, to accommodate three or more channels, depending on the speed of `operation of the teleprinters at the receiving ends of the system. The message signals may be generated by two independent remote teleprinters, telegraph'keys, etc. If the message traiiic originates at two remote independent points, it will be delivered to two independent reperfonators at the transmitting terminal of the system. The transmitting terminal employs a distributor transmitter having separate groups of sending segments assigned to .transmit message signals from the respective reperforators. The message signals are stored in five-unit code form on the perforated tape and transmitted by the distributor transmitter at a predetermined maximum rate. In the system to be described this speed is set at 380 characters per minute. `Each burst of transmission will consist of 402 operations and is more or less an arbitrary number. Because the speed of the distributortransmitter is xed at 380 operations per minute each burst will persist for just over three seconds longer than one minute. Of the 402 operations per burst the first operation will contain the starting and alignment signals vfor setting lthe receiving terminal in motion, lwhile the 402nd operation is an idling one to allow the receiving operations to cease. The remaining four hundred operations are allotted to the transmission of intelligence and an occasional blank amounting, on the average, to about twelve in number. As the speed of the distant keyboard motors change because of variation in frequency of .the public utility, the number of blanks per burst will vary slightly.

The Sending Multiplex Terminal FIGS. 1 and 2 show a sending multiplex terminal which may be employed in the system for passing bursts of four hundred pulses preceded by spacing, starting and alignment pulses according to the invention. The terminal includes two multiplex telegraph transmitters 10 and 12, a two-level stepping switch 14 having four hundred two positions, a two-channel multiplex distributor transmitter 16, and control relays RY1-RY12.

The distributor transmitter includes a stable oscillator 20 which provides a standard frequency source .for energizing motor 22. The motor drives rotor 24. The rotor carries sending brush 26 and local ring brush 28. Brush 26 passes over a ring 23 of ten segments Al-AS and B1- B and an adjacent continuous ring 25. Brush 28 passes over segments AS and BS in one path and a continuous ring 27 in an adjacent path. The rotor 24 of the twochannel multiplex distributor transmitter is driven at 380 r.p.m. by motor 22 which is pulsed by oscillator 20. The oscillator is free running and should have a frequency stability of one cycle in 200,000 or better. The two-level four hundred two step rotary switch 14 serves as a pulse counter. The two multiplex transmitters and 12 are assoicated with perforators 30, 32 which automatically perforate tapes 11, 13, respectively, in response to telegraph signals applied via lines 18, 19 from teleprinters, keys or other sources. The signals are applied to the reperforators at 368 characters per minute. The unperforated tape is carried on reels 34 and 36 and is drawn through the perforators by the sprocket wheels (not shown) which engage in the centrally located sprocket holes in the tapes.. Spaced from the perforators are sensing members 42, 44, each of which has tive sensing pins P for use in detecting tive element code characters on the tape. The tapes leaving the perforators are drawn taut by sprocket wheels in the sensing members engaging in holes 15 of the tapes. These sensing members may be of conventional type such as described in U.S. Patent to G. R. Benjamin 1,298,440.

Automatic transmitting stopping devices are associated with the transmitters 10 and 12. These include auto-stop arms 46 and 48 pivoted to contact the respective tapes when they are held taut. Arms 46, 48 operate switches SW1 and SW2. The switch contacts 50 and 52 are normally open when the tapes are taut and the arms 46, 48 are raised.

In describing operation of the sending terminal it will be assumed no message signal traic is waiting. The auto-stop arms are resting or riding on the taut tapes and both transmitters are auto-stopped, that is, their magnets MA and MB are energized, the pins P at sensing members 42, 44 are retracted, and the live unit contacts 54 and 56 rest on positive and negative busbars 58 and 60 respectively.

In this idling condition, the segmented ring 23 passes current alternations or reversals to outgoing telegraph line 62 continuously, five successive positive pulses being applied from the A channel transmitter 10 and live negative pulses being applied from the B channel transmitter 12 during each revolution of rotor 24. Both sensing arms SAI and SA2 which are operated together by switch bar 21 connected to ratchet bar 70 of stepper switch 14, rest on the first stud S1 and S1 of the two switch levels. The circuit of the switch stepper magnet MC is open since stud S1 is now connected to open paralleled contacts 64, 66 of relays RYl and RY2 respectively. These relays follow the contact operation of switches SW1 and SW2 as controlled by their respective auto-stop arms 46 and 48.

, Differential relays RY11 and RY12 are held operated through their right-hand coils and energize the transmitter magnets MA and MB with steady direct current. All relays RY1-RY10 are released.

When message traic is waiting to be sent from either reperforator 30 or 32, its tape will slacken to form a loop 11' or 13 whereupon the arm 46 or 48 will drop and contacts of the associated switch will close. Suppose channel A wishes to send message signals. Auto-stop contacts 50 will close as arm 46 drops to energize relay RY1. As the local ring brush 28 in the distributor transmitter 16 passes over stepping segment C, the magnet MC will 4. move the ratchet 68 to the next tooth on ratchet bar 70 in switch 14, the circuit of magnet MC being closed through contacts 64 of relay RYI, stud S1, wiper arm SAI, bar 72, segment C and ring 27. The magnet circuit is broken as the brush 28 passes segment C and spring 74 advances the ratchet and ratchet bar one step. As the ratchet bar advances, wiper arms SAI and SA2 will ad- Vance to studs S2 and S2 on their respective switch levels. With arm SA2 on stud S2' relays RYS and RY6 will operate opening their normally closed contacts 80, 82 to open the left-hand coil circuits of the dilerential relays RY7 and RYB. When brush 28 then passes over segment AS, relay RY7 will be pulsed and will lock up to operate A.C. relay RY3 via contacts 84 of relay RY7. When the brush next passes over segment BS, relay RYS will similarly be pulsed to lock up and operate A.C. relay RY4 via contacts 86 of relay RY8.

Relays RYS and RY4 operate to cause alternating pulses to be applied to the sending segments 23 of each channel. This is accomplished because of the positive polarity applied to contacts C1, C3, C5, C2', C4' of the relays while negative battery polarity is applied to contacts C2, C4, C1', C3' and C5. This produces the A.C. alignment signal used to start the receiving terminal and upon which that terminal centers the scanning of the signals.

During the rst revolution of rotor 24, the relays RY11 and RY12 are energized as current passes only through the right-hand coils of the relays. The left-hand coils are not energized because of the open contacts 88 and 90 in relays RY9 and RYIO. When brush 28 passes over segment C for the second time, the ratchet operates the wipers SAI and SA2 through studs S2 and S2 to studs S3 and S3. This immediately operates relays RY9 and RY10 and releases RYS and RY6. Thus when the brush 28 reaches segment AS, relay RY7 is released because the currents in its coils are now equal and opposite. This deenergizes and drops relay RY3 restoring the segments A1-A5 to the transmitter contacts 54 via contacts Cl-CS. At the same time equal and opposite currents appear in relay RY11 because of the closure of contacts 88 in relay RY9, 65 in relay RY1 and 91, 92 in relay RY11. Relay RY11 releases to open contacts 91, 93 and close contacts 91, 92 and when the brush passes oil segment AS the sensing pins P in sensing member 42 operate the transmitter contacts 54 to close the marking circuit through bus 59 in accordance with the code of the character then in place on the tape 11.

When brush 28 passes over segment BS, relay RY8 is released in a manner similar to relay RY7 to restore the channel B segments Bl-BS fto the channel B transmitter 12 through contacts CILCS. However, because the tape 13 is ltaut between the reperforator 32 and the sensing member 44, relay RY2 is released and maintains an open circuit for the lent-hand coil of RY12. The latter remains operated and the magnet MB remains energized.

`On subsequent revolutions of the distributor transmitters 10 or 12 can cut in `or cut out at will depending on Whether the loops of tapes l'11 and 13 are slack or taut. Wiper arms SAI and SA2 will complete four hundred two 4steps in passing studs S1S402 and S1S402 respectively. When the wiper arms are again stepped to studs S1 and S1', relays RY9 Vand RY11) are released and on the next distributor revolution relays RY11 and RY12 are both operated to energize magnets MA and MB thus auto-stopping both the transmitters regardless of whether message traflic is waiting t-o be sent, so that a full revoluf Y tion of channel spacing is sent. 

1. A COMMUNICATIONS SYSTEM COMPRISING SENDING AND RECEIVING TERMINALS FOR MESSAGE SIGNALS, MEANS FOR GENERATING A SERIES OF SAID MESSAGE SIGNALS AT THE SENDING TERMINAL, MEANS FOR REPEATEDLY INTERRUPTING SAID MESSAGE SIGNALS AND GENERATING GROUPS OF ALTERNATING PULSES AT THE SENDING TERMINAL, EACH GROUP OF PULSES BEING GENERATED AFTER A BURST OF A PREDETERMINED NUMBER OF SAID MESSAGE SIGNALS, RECEIVING MEANS AT THE RECEIVING TERMINAL RESPONSIVE TO SAID MESSAGE SIGNALS FOR RECORDING THE SAME, CIRCUIT CONTROL MEANS AT THE RECEIVING TERMINAL RESPONSIVE TO SAID ALIGNMENT SIGNALS FOR STARTING AND STOPPING SAID RECEIVING MEANS IN COORDINATION WITH THE BEGINNING AND END OF EACH BURST OF MESSAGE SIGNALS GENERATED AT THE SENDING TERMINAL, EACH GROUP OF SAID PULSES CONSISTING OF A FIXED NUMBER OF PULSES, AN OSCILLATOR AT THE RECEIVING TERMINAL GENERATING FIXED FREQUENCY CYCLIC CONTROL SIGNALS, MEANS IN CIRCUIT WITH SAID OSCILLATOR FOR PRODUCING A MULTIPLICITY OF ALTERNATING VOLTAGE GATE PULSES DURING EACH CYCLE OF THE CONTROL SIGNALS, MEANS FOR SCANNING THE GATE PULSES TO OBTAIN AN OUTPUT PULSE AT THE CENTER OF A SERIES OF COINCIDENCES OF TRANSITIONS THROUGH ZERO AMPLITUDE OF THE PULSES IN EACH GROUP THEREOF WITH A GROUP OF THE GATE PULSES, AND MEANS FOR APPLYING SAID OUTPUT PULSE TO SAID RECEIVING MEANS FOR STARTING THE SAME AT THE INSTANT OF STARTING EACH BURST OF MESSAGE SIGNALS. 